Adding to Miki’s reply to your post -
Some devices / apps make recording easy via USB or network storage - so may help if you provide more info about the device / app you are using.
Do you intend to keep these recordings or is it just to watch something that is on different channels at the same time?
If it is the latter, then a service that offers catchup could be your perfect answer - catchup is offered for popular channels and normally you can rewatch a broadcast from upto 7 days depending on your service
see -